Optical Path Design

Optical design determines system structures, performance, dimensions, and alternative solutions from customer operating conditions. We offer distinctive professional designs for volume customization. Four stages are dimensional calculations, initial structures, aberration correction/balancing, and image-quality evaluation. Dimensions: establish the schematic and basic characteristics—magnification/focal length, linear/angular field, NA/relative aperture, conjugates, rear working distance, stop location, and overall size—to meet requirements. Account for mechanics/electronics to ensure feasibility. Excess requirements cause complexity/waste; insufficient ones fail needs. Initial structures: derive from primary-aberration theory or select existing designs. Existing designs are practical and often successful but require deep theory/experience to choose a simple suitable structure. Poor starting structures cannot be rescued by good automatic programs or experienced designers. Correction/balancing: analyze and ray-trace the selected structure using ZEMAX, CODEⅤ, etc., calculating aberrations/curves. Identify dominant image-quality errors, develop improvements, and iterate until requirements are met. Evaluation: image quality depends on aberration. All aberrations neither can nor need be zero; residuals remain and affect quality. Designers must understand allowable residuals/tolerances to assess systems. Methods include: Rayleigh criterion—maximum actual-to-ideal wavefront difference ≤1/4 wavelength, a strict method for small-aberration telescopes/objectives. Optical transfer function MTF—the object is treated as a spectrum of frequencies, and optics as a linear invariant system. Imaging transfers sinusoidal distributions at unchanged frequency but reduced contrast. Frequency-dependent contrast reduction/phase shifts define the optical transfer function. Since it depends on aberration, it objectively/reliably evaluates images and is readily calculated/measured. It evaluates designs and also controls design processes, lens inspection, and overall optical design.

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